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The Mid-infrared E-ELT Thermal Infrared imager and Spectrograph (METIS) is one of the three first-light instruments selected for the European Extremely Large Telescope (ELT) and will cover the thermal infrared wavelength range, from ca. 3 - 13 microns. It will be a versatile instrument featuring diffraction-limited imaging and long-slit spectroscopy in the L/M and N bands as well as high spectral resolution (R ~ 100,000) integral field spectroscopy in the L and M bands. Its spatial resolution of 25 (70) mas in the L (N) band corresponds to a linear scale of 1 (3) parsec in nearby (10 Mpc) galaxies. For nearby AGNs, METIS forms the missing link between JWST and ground-based interferometry in both resolution and sensitivity. METIS will primarily observe continuum emission from dust at 100-800 K, but it will also be sensitive to the emission lines in this wavelength range, e.g. Brackett alpha, coronal lines like [SiIX] and [ArVI] and [AlVI], molecular lines of CO and H2O, and broad silicate emission and absorption lines. As such it is well matched to tackle several of the outstanding questions in current AGN research including "What triggers AGN activity?" and "How do AGN outflows connect to the host galaxy?". In this talk, I review METIS' instrumental capabilities with a particular focus on the prospects for AGN research.

著者人数: 19名, Accepted: 2011-02-08, 資料番号: SA1002748000

著者人数: 18名, Accepted: 2010-07-30, 資料番号: SA1002745000

International audience; The relationship between galaxy star formation rates (SFRs) and stellar masses (M*) is reexamined using a mass-selected sample of similar to 62,000 star-forming galaxies at z \textless= 1.3 in the COSMOS 2 deg2 field. Using new far-infrared photometry from Herschel-PACS and SPIRE and Spitzer-MIPS 24 mu m, along with derived infrared luminosities from the NRK method based on galaxies' locations in the restframe color-color diagram (NUV - r) versus (r - K), we are able to more accurately determine total SFRs for our complete sample. At all redshifts, the relationship between median SFR and M* follows a power law at low stellar masses, and flattens to nearly constant SFR at high stellar masses. We describe a new parameterization that provides the best fit to the main sequence and characterizes the low mass power-law slope, turnover mass, and overall scaling. The turnover in the main sequence occurs at a characteristic mass of about M-0 similar to 10(10) M-circle dot at all redshifts. The low mass power-law slope ranges from 0.9-1.3 and the overall scaling rises in SFR as a function of (1+z)(4.12 +/- 0.10). A broken power-law fit below and above the turnover mass gives relationships of SFR proportional to M*(0.88 +/- 0.06) below the turnover mass and SFR proportional to M*(0.27 +/- 0.04) above the turnover mass. Galaxies more massive than M* greater than or similar to 10(10)M(circle dot) have a much lower average specific star formation rate (sSFR) than would be expected by simply extrapolating the traditional linear fit to the main sequence found for less massive galaxies.

International audience; Using the first 50% of data collected for the Spitzer Large Area Survey with Hyper-Suprime-Cam observations on the 1.8 deg(2) Cosmological Evolution Survey we estimate the masses and star formation rates of 3398M(*) \textgreater 10(10) M-circle dot star-forming galaxies at 4 \textless z \textless 6 with a substantial population up to M-* greater than or similar to 10(11.5) M-circle dot. We find that the strong correlation between stellar mass and star formation rate seen at lower redshift (the “main sequence” of star-forming galaxies) extends to z similar to 6. The observed relation and scatter is consistent with a continued increase in star formation rate at fixed mass in line with extrapolations from lower-redshift observations. It is difficult to explain this continued correlation, especially for the most massive systems, unless the most massive galaxies are forming stars near their Eddington-limited rate from their first collapse. Furthermore, we find no evidence for moderate quenching at higher masses, indicating quenching either has not occurred prior to z similar to 6 or else occurs rapidly, so that few galaxies are visible in transition between star-forming and quenched.

In order to constrain the bolometric luminosities, dust properties, and molecular gas content of giant Lyα nebulae, the so-called Lyα blobs, we have carried out a study of dust continuum and CO line emission in two well-studied representatives of this population at z ~ 3: an Lyα blob discovered by its strong Spitzer Multiband Infrared Photometer 24 μm detection (LABd05) and the Steidel blob 1 (SSA22-LAB01). We find that the spectral energy distribution of LABd05 is well described by an active-galactic-nucleus-starburst composite template with L_(FIR) = (4.0 ± 0.5) × 10^(12) L_☉, comparable to high-z submillimeter galaxies and ultraluminous infrared galaxies. New Large APEX Bolometer Camera 870 μm measurements rule out the reported Submillimeter Common-User Bolometer Array detection of the SSA22-LAB01 (S_(850 μm) = 16.8 mJy) at the >4σ level. Consistent with this, ultradeep Plateau de Bure Interferometer observations with ~2'' spatial resolution also fail to detect any 1.2 mm continuum source down to ≈0.45 mJy beam^(–1) (3σ). Combined with the existing (sub)millimeter observations in the literature, we conclude that the FIR luminosity of SSA22-LAB01 remains uncertain. No CO line is detected in either case down to integrated flux limits of S_νΔV ≾ 0.25-1.0 Jy km s^(–1), indicating a modest molecular gas reservoir, M(H_2) < (1-3) × 10^(10) M_☉. The non-detections exclude, with high significance (12σ), the previous tentative detection of a CO J = 4-3 line in the SSA22-LAB01. The increased sensitivity afforded by the Atacama Large Millimeter/submillimeter Array will be critical in studying molecular gas and dust in these interesting systems.

By cross-correlating AKARI all sky survey in 6 infrared (IR) bands (9, 18, 65, 90, 140, and 160μm) with the SDSS galaxies, we identified 2357 infrared galaxies with a spectroscopic redshift. This is not just one of the largest samples of local IR galaxies, but AKARI provides crucial FIR bands in accurately measuring galaxy SED across the peak of the dust emission at > 100μm. By fitting modern IR SED models to the AKARI photometry, we measured the total infrared luminosity (LIR) of individual galaxies. \ud Using this LIR, we constructed the luminosity functions of infrared galaxies at a median redshift of z=0.031. The LF agrees well with that at z=0.0082 (the RBGS), showing smooth and continuous evolution toward higher redshift LFs measured in the AKARI NEP deep field. By integrating the IR LF weighted by LIR, we measured the local cosmic IR luminosity density of IR= (3.8+5.8−1.2) × 108 L⊙Mpc−3.\ud \ud We separate galaxies into AGN (active galactic nuclei), star-forming, and composite by using the [NII]/Hα vs [OIII]/Hβ line ratios. The fraction of AGN shows a continuous increase with increasing LIR from 25% to 90% at 9< log LIR Hα and L[OIII] show good correlations with LIR for SFG (star-forming galaxies) and AGN, respectively. The self-absorption corrected Hα/Hβ ratio shows a weak increase with LIR with a substantial scatter. When we separate IR LFs into contributions from AGN and star-forming galaxies (SFG), the AGN contribution becomes dominant at LIR > 1011L⊙, coinciding the break of the both SFG and AGN IR LFs. At LIR ≤ 1011L⊙, SFG dominates IR LFs. Only 1.1±0.1% of Ω IR is produced by LIRG (LIR > 1011L⊙), and only 0.03±0.01% is by ULIRG (LIR > 1012L⊙) in the local Universe. Compared with high redshift results from the AKARI NEP deep survey, we observed a strong evolution of ΩSFGIR α(1+z)4.1±0.4 and ΩAGNIR α(1+z)4.1±0.5. Our results show all of our measured quantities (IR LFs, L∗, ΩAGNIR, ΩSFGIR) show smooth and steady increase from lower redshift (the RBGS) to higher redshift (the AKARI NEP deep survey).

By cross-correlating the AKARI all-sky survey in six infrared (IR) bands (9, 18, 65, 90, 140 and 160 μm) with the Sloan Digital Sky Survey (SDSS) galaxies, we identified 2357 IR galaxies with a spectroscopic redshift. This is not just one of the largest samples of local IR galaxies, but AKARI provides crucial far-IR (FIR) bands for accurately measuring the galaxy spectral energy distribution (SED) across the peak of the dust emission at > 100 μ m. By fitting modern IR SED models to the AKARI photometry, we measured the total infrared luminosity (L_(IR)) of individual galaxies. Using this L_(IR), we constructed the luminosity functions (LF) of IR galaxies at a median redshift of z= 0.031. The LF agrees well with that at z= 0.0082 (the Revised Bright Galaxy Sample), showing smooth and continuous evolution towards higher redshift LFs measured in the AKARI North Ecliptic Pole (NEP) deep field. By integrating the IR LF weighted by L_(IR), we measured the local cosmic IR luminosity density of Ω_(IR_= (3.8^(+5.8)_(−1.2)) × 10^8 L_⊙ Mpc^(−3). We separate galaxies into active galactic nuclei (AGN), star-forming galaxies (SFG) and composite by using the [N ii]/Hα versus [O iii]/Hβ line ratios. The fraction of AGN shows a continuous increase with increasing L_(IR) from 25 to 90 per cent at 9 < log L_(IR) < 12.5. The SFR_(Hα) and L_([OΙΙΙ]) show good correlations with L_(IR) for SFG and AGN, respectively. The self-absorption-corrected Hα/Hβ ratio shows a weak increase with LIR with a substantial scatter. When we separate IR LFs into contributions from AGN and SFG, the AGN contribution becomes dominant at L_(IR) > 10^(11) L_⊙, coinciding with the break of both the SFG and AGN IR LFs. At L_(IR)≤ 10^(11) L_⊙, SFG dominates IR LFs. Only 1.1 ± 0.1 per cent of Ω_(IR) is produced by luminous infrared galaxies (L_(IR) > 10^(11) L_⊙), and only 0.03 ± 0.01 per cent by ultraluminous infrared galaxies (L_(IR) > 10^(12) L_⊙) in the local Universe. Compared with high-redshift results from the AKARI NEP deep survey, we observed a strong evolution of Ω^(SFG)IR^∝ (1 +z)^(4.1±0.4) and Ω^(AGN)IR^∝ (1+z)^(4.1±0.5). Our results show that all of our measured quantities (IR LFs, L^*, Ω^(AGN)IR, Ω^(SFG)IR) show smooth and steady increase from lower redshift (the Revised Bright Galaxy Sample) to higher redshift (the AKARI NEP deep survey).

Infrared (IR) luminosity is fundamental to understanding the cosmic star formation history and active galactic nuclei (AGN) evolution, since their most intense stages are often obscured by dust. However, local IR luminosity function estimates today are still based on the IRAS survey in the 1980s, with wavelength coverage only up to 100 μm. The AKARI IR space telescope performed an all-sky survey in six IR bands (9, 18, 65, 90, 140 and 160 μm) with 3–10 times better sensitivity, covering the crucial far-IR wavelengths across the peak of the dust emission. Combined with a better spatial resolution, AKARI can much more precisely measure the total infrared luminosity (L_(TIR)) of individual galaxies, and thus, the total infrared luminosity density in the local Universe. By fitting modern IR spectral energy distribution (SED) models, we have remeasured L_(TIR) of the IRAS Revised Bright Galaxy Sample, which is a complete sample of local galaxies with S_(60μm) > 5.24 Jy. We present mid-IR monochromatic luminosity (νL_ν) to L_(TIR) correlations for Spitzer 8 μm, AKARI 9 μm, IRAS 12 μm, WISE 12 μm, ISO 15 μm, AKARI 18 μm, WISE 22 μm and Spitzer 24 μm filters. These measures of L_(MIR) are well correlated with L_(TIR), with scatter in the range 13–44 per cent. The best-fitting L_(MIR)-to-L_(TIR) conversions provide us with estimates of L_(TIR) using only a single MIR band, in which several deep all-sky surveys are becoming available such as AKARI MIR and WISE. Although we have found some overestimates of L_(TIR) by IRAS due to contaminating cirrus/ sources, the resulting AKARI IR luminosity function (LF) agrees well with that from IRAS. We integrate the LF weighted by L_(TIR) to obtain a cosmic IR luminosity density of Ω_(TIR) = (8.5^(+1.5)_(−2.3)) × 10^7 L_⊙ Mpc^(−3), of which 7 ± 1 per cent is produced by luminous infrared galaxies (LIRGs) (L_(TIR) > 10^(11) L_⊙), and only 0.4 ± 0.1 per cent is from ultraluminous infrared galaxies (ULIRGs) (L_(TIR) > 10^(12) L_⊙) in the local Universe, in stark contrast to high-redshift results. We separate the contributions from AGN and star-forming galaxies (SFGs). The SFG IR LF shows a steep decline at the bright end. Combined with high-redshift results from the AKARI NEP deep survey, these data show a strong evolution of Ω^(SF)_(TIR) ∝ (1 + z)^(4.0 ± 0.5) and Ω^(AGN)_(TIR) ∝ (1 + z)^(4.4 ± 0.4). For Ω^(AGN)_(TIR), the ULIRG contribution exceeds that from LIRGs already by z ~ 1. A rapid evolution in both Ω^(AGN)_(TIR) and Ω^(SFG)_(TIR) suggests the correlation between star formation and black hole accretion rate continues up to higher redshifts. We compare the evolution of Ω^(AGN)_(TIR) to that of X-ray luminosity density. The Ω^(AGN)_(TIR)/Ω^(AGN)_(X-ray) ratio shows a possible increase at z > 1, suggesting an increase of obscured AGN at z > 1.

We present Spitzer 16μm imaging of the Great Observatories Origins Deep Survey (GOODS) fields. We survey 150 arcmin^2 in each of the two GOODS fields (North and South), to an average 3σ depth of 40 and 65 μJy, respectively. We detect ~1300 sources in both fields combined. We validate the photometry using the 3–24μm spectral energy distribution of stars in the fields compared to Spitzer spectroscopic templates. Comparison with ISOCAM and AKARI observations in the same fields shows reasonable agreement, though the uncertainties are large. We provide a catalog of photometry, with sources cross-correlated with available Spitzer, Chandra, and Hubble Space Telescope data. Galaxy number counts show good agreement with previous results from ISOCAM and AKARI with improved uncertainties. We examine the 16–24μm flux ratio and find that for most sources it lies within the expected locus for starbursts and infrared luminous galaxies. A color cut of S_(16)/S_(24) > 1.4 selects mostly sources which lie at 1.1 < z < 1.6, where the 24μm passband contains both the redshifted 9.7 μm silicate absorption and the minimum between polycyclic aromatic hydrocarbon emission peaks. We measure the integrated galaxy light of 16μm sources and find a lower limit on the galaxy contribution to the extragalactic background light at this wavelength to be 2.2 ± 0.2 nW m^(−2) sr^(−1).

We present ultra-deep mid-infrared spectra of 48 infrared-luminous galaxies in the GOODS-south field obtained with the Infrared Spectrograph on the Spitzer Space Telescope. These galaxies are selected among faint infrared sources (0.14-0.5 mJy at 24 μm) in two redshift bins (0.76-1.05 and 1.75-2.4) to sample the major contributors to the cosmic infrared background at the most active epochs. We estimate redshifts for 92% of the sample using polycyclic aromatic (PAH) and Si absorption features obtaining, in particular, eight new redshifts difficult to measure from ground-based observations. Only a few of these galaxies (5% at z ~ 1 and 12% at z ~ 2) have their total infrared luminosity dominated by emission from active galactic nuclei (AGNs). The averaged mid-IR spectrum of the z ~ 1 luminous infrared galaxies (LIRGs) is a very good match to the averaged spectrum of local starbursts. The averaged spectrum of the z ~ 2 ultra-luminous infrared galaxies (ULIRGs), because of a deeper Si absorption, is better fitted by the averaged spectrum of H II-like local ULIRGs. Combining this sample with other published data, we find that 6.2 μm PAH equivalent widths (EW) reach a plateau of ~ 1 μm for L 24 μm ≾ 10^(11) L_⊙. At higher luminosities, EW_(6.2 μm) anti-correlates with L _(24 μm). Intriguingly, high-z ULIRGs and sub-millimeter galaxies (SMGs) lie above the local EW_(6.2 μm)-L_(24 μm) relationship suggesting that, at a given luminosity, high-z ULIRGs have AGN contributions to their dust emission lower than those of local counterparts. A quantitative analysis of their morphology shows that most of the luminous IR galaxies have morphologies similar to those of IR-quiet galaxies at the same redshift. All z ~ 2 ULIRGs of our sample are IR-excess BzK galaxies and most of them have L_(FIR)/L_(1600 Å) ratios higher than those of starburst galaxies at a given UV slope. The "IR excess" is mostly due to strong 7.7 μm PAH emission and underestimation of UV dust extinction. On the basis of the AGN-powered L_(6 μm) continuum measured directly from the mid-IR spectra, we estimate an average intrinsic X-ray AGN luminosity of L_(2–10 keV) = (0.1± 0.6)× 10^(43) erg s^(–1), a value substantially lower than the prediction by Daddi et al.

We present a study of the average properties of luminous infrared galaxies detected directly at 24 μm in the COSMOS field using a median stacking analysis at 70 μm and 160 μm. Over 35,000 sources spanning 0 ≤ z ≤ 3 and 0.06 mJy ≤ S_(24) ≤ 3.0 mJy are stacked, divided into bins of both photometric redshift and 24 μm flux. We find no correlation of S_(70)/S_(24) flux density ratio with S_(24), but find that galaxies with higher S_(24) have a lower S_(160)/S_(24) flux density ratio. These observed ratios suggest that 24 μm selected galaxies have warmer spectral energy distributions (SEDs) at higher mid-IR fluxes, and therefore have a possible higher fraction of active galactic nuclei. Comparisons of the average S_(70)/S_(24) and S_(160)/S_(24) colors with various empirical templates and theoretical models show that the galaxies detected at 24 μm are consistent with "normal" star-forming galaxies and warm mid-IR galaxies such as Mrk 231, but inconsistent with heavily obscured galaxies such as Arp 220. We perform a χ^2 analysis to determine best-fit galactic model SEDs and total IR luminosities for each of our bins. We compare our results to previous methods of estimating L IR and find that previous methods show considerable agreement over the full redshift range, except for the brightest S_(24) sources, where they overpredict the bolometric IR luminosity at high redshift, most likely due to their warmer dust SED. We present a table that can be used as a more accurate and robust method for estimating bolometric infrared luminosity from 24 μm flux densities.

International audience; We present a study of the average properties of luminous infrared galaxies detected directly at 24 mu m in the COSMOS field using a median stacking analysis at 70 mu m and 160 mu m. Over 35,000 sources spanning 0 \textless= z \textless= 3 and 0.06 mJy \textless= S(24) \textless= 3.0 mJy are stacked, divided into bins of both photometric redshift and 24 mu m flux. We find no correlation of S(70)/S(24) flux density ratio with S(24), but find that galaxies with higher S(24) have a lower S(160)/S(24) flux density ratio. These observed ratios suggest that 24 mu m selected galaxies have warmer spectral energy distributions (SEDs) at higher mid-IR fluxes, and therefore have a possible higher fraction of active galactic nuclei. Comparisons of the average S(70)/S(24) and S(160)/S(24) colors with various empirical templates and theoretical models show that the galaxies detected at 24 mu m are consistent with “normal” star-forming galaxies and warm mid-IR galaxies such as Mrk 231, but inconsistent with heavily obscured galaxies such as Arp 220. We perform a chi(2) analysis to determine best-fit galactic model SEDs and total IR luminosities for each of our bins. We compare our results to previous methods of estimating L(IR) and find that previous methods show considerable agreement over the full redshift range, except for the brightest S(24) sources, where they overpredict the bolometric IR luminosity at high redshift, most likely due to their warmer dust SED. We present a table that can be used as a more accurate and robust method for estimating bolometric infrared luminosity from 24 mu m flux densities.

Using the Infrared Spectrograph on board the Spitzer Space Telescope, we present low-resolution (64 < λ/δλ < 124), mid-infrared (20-38 μm) spectra of 23 high-redshift ULIRGs detected in the Boötes field of the NOAO Deep Wide-Field Survey. All of the sources were selected to have (1) f_ν(24 μm)>0.5 mJy; (2) R – [24]>14 Vega mag; and (3) a prominent rest frame 1.6 μm stellar photospheric feature redshifted into Spitzer's 3-8 μm IRAC bands. Of these, 20 show emission from polycyclic aromatic hydrocarbons (PAHs), usually interpreted as signatures of star formation. The PAH features indicate redshifts in the range 1.5 < z < 3.0, with a mean of = 1.96 and a dispersion of 0.30. Based on local templates, these sources have extremely large infrared luminosities, comparable to that of submillimeter galaxies. Our results confirm previous indications that the rest-frame 1.6 μm stellar bump can be efficiently used to select highly obscured star-forming galaxies at z ≈ 2, and that the fraction of starburst-dominated ULIRGs increases to faint 24 μm flux densities. Using local templates, we find that the observed narrow redshift distribution is due to the fact that the 24 μm detectability of PAH-rich sources peaks sharply at z = 1.9. We can analogously use observed spectral energy distributions to explain the broader redshift distribution of Spitzer-detected ULIRGs that are dominated by an active galactic nucleus (AGN). Finally, we conclude that z ≈ 2 sources with a detectable 1.6 μm stellar opacity feature lack sufficient AGN emission to veil the 7.7 μm PAH band.

The relationship between galaxy star formation rates (SFRs) and stellar masses (M ) is reexamined using a mass selected sample of 62000 star forming galaxies at z 1010 M ? have a much lower average specific star formation rate (sSFR) than would be expected by simply extrapolating the traditional linear fit to the main sequence found for less massive galaxies.